TiVo Community
TiVo Community
TiVo Community
Go Back   TiVo Community > Main TiVo Forums > TiVo Coffee House - TiVo Discussion
TiVo Community
Reply
Forum Jump
 
Thread Tools
Old 02-05-2009, 05:56 AM   #31
bicker
Gruff
 
Join Date: Nov 2003
Location: Alpharetta, GA
Posts: 9,144
Quote:
Originally Posted by ciper View Post
... TiVo are spending time on useless features rather than those . . .
. . . features that ciper wants.

There.... fixed your post.
bicker is offline   Reply With Quote
Old 02-05-2009, 06:05 AM   #32
bicker
Gruff
 
Join Date: Nov 2003
Location: Alpharetta, GA
Posts: 9,144
Quote:
Originally Posted by ZeoTiVo View Post
the series 2 boxes do not seem to have many problems, it is the world of digital, HD and cable cards that have proven to be tough for a standalone DVR company.
While the highlighted portion of what you've written is absolutely on-target, you don't even go far enough IMHO. Go over to avsforum.com, or any of a half-dozen other discussion forums where I've seen posters complain about every single cable company-owned DVR out there, as much if not more so than posters complain about TiVo, here. If folks have problems with the TiVo HD, let them go find another ATSC and QAM capable, CableCARD-compatible, HD DVR that does more, with fewer problems, for less money.

I personally don't recommend folks buy the TiVo HD, these days, but that's because I think that it is too close to the introduction of tru2way to make a big purchase like that worthwhile. However, if someone is going to buy their own HD DVR, despite my advice not to, then I couldn't imagine recommending the Moxi (too much more expensive, and too much of an unknown quantity, going forward, at this point), or the DTVPal DVR (no CableCARD). I'm not going to send them on project to learn enough to build and maintain their own DVR. I'm going to tell them to stick with a known quantity, made for the average American consumer's consumption, the TiVo.
bicker is offline   Reply With Quote
Old 02-05-2009, 06:07 AM   #33
ciper
Registered User
 
Join Date: Nov 2004
Posts: 2,010
Quote:
Originally Posted by bicker View Post
. . . features that ciper wants.

There.... fixed your post.
I'm fairly certain everyone wants a working 1x fast forward. I can't see how anyone wouldn't. TiVo even knows how to do it,,, the DVD units were updated to get working trick play YEARS ago and it is exactly the same issue!
ciper is offline   Reply With Quote
Old 02-05-2009, 06:08 AM   #34
bicker
Gruff
 
Join Date: Nov 2003
Location: Alpharetta, GA
Posts: 9,144
Read the post you replied to in context. You wrote the sentence about what new features TiVo is "spending time" on.

Try to keep up, will you.
bicker is offline   Reply With Quote
Old 02-05-2009, 06:20 AM   #35
ciper
Registered User
 
Join Date: Nov 2004
Posts: 2,010
Quote:
Originally Posted by bicker View Post
Read the post you replied to in context. You wrote the sentence about what new features TiVo is "spending time" on.

Try to keep up, will you.
Quote:
Originally Posted by ciper
admit the boxes have many bugs and that TiVo are spending time on useless features rather than those that would help sales.
1x fast forward that works is a feature that would help sell more units. Right now only S1 and S2 boxes have a fully functional fast forward.

The recent addition of skip back on 1x FF makes it even more painful.
ciper is offline   Reply With Quote
Old 02-05-2009, 06:37 AM   #36
bicker
Gruff
 
Join Date: Nov 2003
Location: Alpharetta, GA
Posts: 9,144
Again, try to keep up: TiVo is not spending any time developing a 1x fast-forward feature.
bicker is offline   Reply With Quote
Old 02-05-2009, 07:02 AM   #37
ciper
Registered User
 
Join Date: Nov 2004
Posts: 2,010
Quote:
Originally Posted by bicker View Post
Again, try to keep up: TiVo is not spending any time developing a 1x fast-forward feature.
Exactly. They need to. It shouldn't be very hard considering they already fixed it on DVD TiVo boxes.
ciper is offline   Reply With Quote
Old 02-05-2009, 07:22 AM   #38
bicker
Gruff
 
Join Date: Nov 2003
Location: Alpharetta, GA
Posts: 9,144
Correction: You want them to.
bicker is offline   Reply With Quote
Old 02-05-2009, 09:35 AM   #39
ADGrant
Registered User
 
Join Date: Jul 2002
Posts: 73
I put my old 1999 Series 1 in the closet in early 2005. I would not be using Tivo now if not for CableCard and the crappy software in CableCo DVRs (SARA, Passport and that new TWC OCAP).

I really don't care about TTG or MRV or Netflix (though I have it working and may use it to watch old BBC shows). The only post Series 1 feature I user regularly is remote scheduling which is great but I would still use Tivo without it. To me the killer Tivo features are the 2 weeks of guide data and the fact that it doesn't record the same show twice (the folders are nice too).
ADGrant is offline   Reply With Quote
Old 02-05-2009, 12:49 PM   #40
Ckought
Registered User
 
Join Date: Nov 2006
Location: Kentucky
Posts: 73
What's the thing about "Viacom Inc.'s Nickelodeon TV shows"? I haven't seen anything about that.
Ckought is offline   Reply With Quote
Old 02-05-2009, 07:19 PM   #41
Dan203
Super Moderator
 
Dan203's Avatar
 
Join Date: Apr 2000
Location: Nevada
Posts: 25,596
Quote:
Originally Posted by ciper View Post
I'm fairly certain everyone wants a working 1x fast forward. I can't see how anyone wouldn't. TiVo even knows how to do it,,, the DVD units were updated to get working trick play YEARS ago and it is exactly the same issue!
These are NOT "exactly the same issue"! The behavior may be similar but the solution is almost certainly not.

I'm not sure if you know how MPEG-2 encoding works but basically there are these groups of frames called GOPs. At the start of every GOP there is an I frame, which is a full frame of video compressed with basically the same technology used for JPEG images. After that there are P and B frames. These frame are not full frames. They only store the differences between them and the previously decoded frame. What this means is that in order for the decoder to display one of the frames in the middle, or at the end, of a GOP it has to first decode all the frames that came before it. (over simplification, but you get the idea)

This system works fine for realtime playback, and even for slightly faster then realtime decoding (depending on the speed of the hardware doing the decoding), but it's impossible to do high speed decoding of every single frame using an inexpensive hardware decoder like TiVo uses. Which means that TiVo is forced to use tricks that allow it to display enough frames to make FF seem smooth while also eliminating enough frames so that it moves at the proper speed.

One trick commonly used for lower speed FF is to simply skip B frames. B frames take the longest to decode, and the P frames can still be decoded without them, so skipping them allows the stream to be decoded significantly faster creating a decently smooth and moderately fast FF speed. However for super high speed FF they usually just display the I frames. Since they are full frames and require minimal power to decompress they can be skipped to and displayed very quickly.

For DVDs there is a strict standard which says that the GOP can be no longer then 18 frames. Which means that they have an I frame every 2/3 second or so and TiVo can use simple I frame decoding to get a decent FF. I think the only reason TiVo had trouble with DVDs was due to media latency and not the streams themselves. DVDs are slow and somewhat erratic to read from. TiVo probably had to employ a little extra buffering and maybe a little timecode monitoring to make FF smooth from DVDs.

Now for digital cable there is no standard. Most cable providers stick to pretty normal GOP lengths and use a repetitive pattern of IBBPBBPBBP... frames so that the tricks above work OK. However I've seen some digital cable recordings that had GOPs 50+ frames long and used an excessive number of B frames to maximize compression. It's those types of streams that TiVo most likely has trouble with, and unfortunately there isn't really anything else they can do to handle them better. It's just a fact of life when you're dealing with a system where you have no control over how the MPEG-2 stream is encoded.

All that being said I've never had any real trouble with FF/RW on my S3. On occasion it will seem like FF is a little faster or slower on certain shows, but it's never enough to totally screw up the whole process. Perhaps the reason it's an issue for you is because your cable company is over compressing the signal to save bandwidth. You should try transferring one of the problem recordings to your PC some time and then opening it in VideoReDo and checking the B/P frame pattern and the GOP length. I bet they either have really long GOPs or erratic and/or excessive use of B frames and that's why FF does work correctly with them.

Dan

P.S. If I had to guess I'd say that TiVo probably uses IP only decoding for 1x FF and I only decoding for 2-3X FF. So even 1x FF could get messed up if a stream has an excessive number of B frames.
__________________
Dan Haddix
Super Moderator
Developer for VideoReDo

Last edited by Dan203 : 02-05-2009 at 07:29 PM.
Dan203 is offline   Reply With Quote
Old 02-06-2009, 09:40 AM   #42
berkshires
Registered User
 
Join Date: Feb 2007
Posts: 440
Quote:
Originally Posted by Dan203 View Post
You should try transferring one of the problem recordings to your PC some time and then opening it in VideoReDo and checking the B/P frame pattern and the GOP length. I bet they either have really long GOPs or erratic and/or excessive use of B frames and that's why FF does work correctly with them.

Dan

P.S. If I had to guess I'd say that TiVo probably uses IP only decoding for 1x FF and I only decoding for 2-3X FF. So even 1x FF could get messed up if a stream has an excessive number of B frames.
That would be interesting. We should have a whole thread devoted just to examining those and observations about FF under different circumstances in the TTG Forum.
berkshires is offline   Reply With Quote
Old 02-06-2009, 04:54 PM   #43
Dan203
Super Moderator
 
Dan203's Avatar
 
Join Date: Apr 2000
Location: Nevada
Posts: 25,596
I agree. If anyone does start such a thread shoot me a PM so I can check it out. (I don't always catch every thread on my own)

Dan
__________________
Dan Haddix
Super Moderator
Developer for VideoReDo
Dan203 is offline   Reply With Quote
Old 02-07-2009, 09:32 AM   #44
HerronScott
Registered User
 
Join Date: Jan 2002
Location: Staunton, VA
Posts: 984
Quote:
Originally Posted by ADGrant View Post
I put my old 1999 Series 1 in the closet in early 2005. I would not be using Tivo now if not for CableCard and the crappy software in CableCo DVRs (SARA, Passport and that new TWC OCAP).

I really don't care about TTG or MRV or Netflix (though I have it working and may use it to watch old BBC shows). The only post Series 1 feature I user regularly is remote scheduling which is great but I would still use Tivo without it. To me the killer Tivo features are the 2 weeks of guide data and the fact that it doesn't record the same show twice (the folders are nice too).
Are you still watching in SD? HD would certainly qualify as a post-Series1 feature (and the primary reason we moved from our Series1 TiVos to Series 3 TiVos when they offered the lifetime transfer).

Scott
HerronScott is offline   Reply With Quote
Old 02-07-2009, 11:52 AM   #45
jrm01
Registered User
 
Join Date: Oct 2003
Location: Pittsburgh
Posts: 2,619
Quote:
Originally Posted by Dan203 View Post

.................................

P.S. If I had to guess I'd say that TiVo probably uses IP only decoding for 1x FF and I only decoding for 2-3X FF. So even 1x FF could get messed up if a stream has an excessive number of B frames.
Wow. Thanks for all the great information. I do get the impression that you know what you're talking about.

My S3 has had problems with the FF ever since 9.3. Starge thing is that FFx1 will start out at realtime, and then if held long enough will finally speed up. Also, on some channels the FFx2 and FFx3 look very choppy, but that is usually on the channels where Comcast has decided to place 3 channels per QAM instead of 2, probably resulting in longer gaps between I-Frames.

Of course, once this problem started I switched to 30-sec skip for the vast majority of my use and don't really miss the FF reliability.
__________________
Comcast, Cox, TW, Charter and BHN are cabal companies.
(That is not a spelling error. Check the definition.
)
jrm01 is offline   Reply With Quote
Reply
Forum Jump




Thread Tools


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Advertisements

TiVo Community
Powered by vBulletin® Version 3.6.8
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
vBulletin Skins by: Relivo Media

(C) 2013 Magenium Solutions - All Rights Reserved. No information may be posted elsewhere without written permission.
TiVoŽ is a registered trademark of TiVo Inc. This site is not owned or operated by TiVo Inc.
All times are GMT -5. The time now is 12:23 PM.
OUR NETWORK: MyOpenRouter | TechLore | SansaCommunity | RoboCommunity | MediaSmart Home | Explore3DTV | Dijit Community | DVR Playground |